Previously, most platforms and cores used in cartridges to hold an endless array of magnetic tape were made in two sections. One piece is a platform serving as a disc base for the tape reel. The other piece is the core around which the tape is wound. The inner turns of the tape are then guided for release of the tape for transport to the magnetic pick-up head. This type of platform and core would be shown in U.S. Pat. No. 3,350,028 to Lear and would be fitted together by a snap fit of the core to the platform.
The U.S. Pat. to Coy, No. 3,617,010 shows a particular modification of a one-piece core and platform with castellated segments on the upper free extremity of the core. This core and platform is molded in a one-piece construction. The castellations are supplied in order to have a flexible, yieldable upper section in order to allow deformation of the upper extremity of the core to aid in release of the tape from the inner spool of the array.
In spite of such improvements, it has been found that it would be desirable to minimize tape drag and to reduce the amount of friction of the tape against the outer surface of the core to eliminate hang-up or catching of the tape as it is released from the inner part of the spool. Additionally, a configuration is desired to provide easier molding and mold release of a one-piece core and platform for tape cartridges by straight ahead molding and having no sliding cores.
Accordingly, an object of the invention is to provide an improved commercially acceptable one-piece core and platform for tape cartridges whereby tape drag is minimized with an accompanying reduction of possibility of hang-up of the tape from the spool.
Another object of the invention is to provide a core configuration such that straight ahead molding techniques may be utilized thereby eliminating mold parting lines resulting from sliding cores which may cause tape hang-up.